Positive Electrode Active Material and Method of Preparing the Same

Abstract

A positive electrode active material and method of preparing the same are disclosed herein. The positive electrode active material can have high capacity and high rate capability. In some embodiments, a positive electrode active material includes lithium transition metal oxide particles having a lithium transition metal oxide represented by Formula 1, wherein an interplanar spacing of (003) crystal planes ((003) d-spacing) of the lithium transition metal oxide of a surface of the particles is larger than a (003) d-spacing of the lithium transition metal oxide inside the particles: wherein 0.8≤a≤1.2, 0.6≤x<1, 0<y<0.4, 0<z<0.4, and 0≤w≤0.1, and M 1 is at least one selected from the group consisting of Al, Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S.

1 . A positive electrode active material, comprising:
 lithium transition metal oxide particles having a lithium transition metal oxide represented by Formula 1,   wherein an interplanar spacing of (003) crystal planes (003) d-spacing) of the lithium transition metal oxide of a surface of the particles is larger than a (003) d-spacing of the lithium transition metal oxide inside the particles:   
       
         
           
           
               
               
           
         
         wherein, in Formula 1, 
         0.8≤a≤1.2, 0.6≤x<1, 0<y<0.4, 0<z<0.4, and 0≤w≤0.1, and 
         M 1  is at least one selected from the group consisting of Al, Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S. 
       
     
     
         2 . The positive electrode active material of  claim 1 , wherein a difference between the (003) d-spacing of the surface of the particles and the (003) d-spacing inside the particles is 0.005 nm or more. 
     
     
         3 . The positive electrode active material of  claim 1 , wherein the (003) d-spacing of the surface of the particles is in a range of 0.46 nm to 0.50 nm, and
 the (003) d-spacing inside the particles is in a range of 0.45 nm to 0.50 nm.   
     
     
         4 . The positive electrode active material of  claim 1 , wherein 0.8≤x<1, 0<y<0.2, and 0<z<0.2. 
     
     
         5 . A method of preparing the positive electrode active material of  claim 1 , the method comprising:
 preparing a multilayer-structured precursor for a positive electrode active material in which two or more of nickel, cobalt, and manganese are precipitated in different regions; and   mixing the multilayer-structured precursor with a lithium raw material and sintering the mixture.   
     
     
         6 . The method of  claim 5 , wherein the preparing of the multilayer-structured precursor comprises:
 performing a co-precipitation reaction while adding a nickel-cobalt metal solution, an ammonium cationic complexing agent, and a basic compound to form nickel-cobalt hydroxide particles in which nickel and cobalt are co-precipitated; and   performing a precipitation reaction while adding a manganese metal solution, an ammonium cationic complexing agent, and a basic compound to a reaction solution containing the nickel-cobalt hydroxide particles to precipitate a manganese hydroxide on the nickel-cobalt hydroxide particles.   
     
     
         7 . The method of  claim 5 , wherein the preparing of the multilayer-structured precursor comprises:
 performing a precipitation reaction while adding a nickel metal solution, an ammonium cationic complexing agent, and a basic compound to form a nickel hydroxide;   performing a precipitation reaction while adding a cobalt metal solution, an ammonium cationic complexing agent, and a basic compound to a reaction solution containing the nickel hydroxide to form a nickel-cobalt hydroxide in which a cobalt hydroxide is precipitated on the nickel hydroxide; and   performing a precipitation reaction while adding a manganese metal solution, an ammonium cationic complexing agent, and a basic compound to a reaction solution containing the nickel-cobalt hydroxide to form nickel-cobalt-manganese hydroxide particles in which the nickel hydroxide, the cobalt hydroxide, and a manganese hydroxide are sequentially precipitated.   
     
     
         8 . The method of  claim 5 , wherein the preparing of the multilayered-structured precursor comprises:
 performing a precipitation reaction while adding a nickel metal solution, an ammonium cationic complexing agent, and a basic compound to form a nickel hydroxide;   performing a precipitation reaction while adding a manganese metal solution, an ammonium cationic complexing agent, and a basic compound to a reaction solution containing the nickel hydroxide to form a nickel-manganese hydroxide in which a manganese hydroxide is precipitated on the nickel hydroxide; and   performing a precipitation reaction while adding a cobalt metal solution, an ammonium cationic complexing agent, and a basic compound to a reaction solution containing the nickel-manganese hydroxide to form nickel-manganese-cobalt hydroxide particles in which the nickel hydroxide, the manganese hydroxide, and a cobalt hydroxide are sequentially precipitated.   
     
     
         9 . A positive electrode comprising the positive electrode active material of  claim 1 . 
     
     
         10 . A lithium secondary battery comprising the positive electrode of  claim 9 .